Document processing devices include printers, copiers, scanners and e-mail gateways. More recently, devices employing two or more of these functions are found in office environments. These devices are referred to as multifunction peripherals (MFPs) or multifunction devices (MFDs). As used herein, MFP means any of the forgoing.
Toner-based print engines use magnetic and electric fields to move toner between the various parts of the print engine. Toner is selectively attracted from a developer roller onto photoconductive drums of an electrostatic process unit (EPU) in accordance with an image to be printed. The TBU transfers the toner from the photoconductive drums onto the paper. And the transferred toner is fused by heat onto the paper which is then delivered to a tray for retrieval by a user. MFPs utilize voltage potentials to transfer toner between the developer rollers, photoconductive drums, transfer belt unit (TBU), and paper.
However, the transfer of toner from the transfer belt onto paper can be affected by the paper's properties such as cellulose content, moisture content, additives such as whiteners, paper thickness, temperature, and so forth. Some MFPs include a manual adjustment for changing the transfer parameters, however the manual adjustment is rarely adjusted, and when the transfer voltage is adjusted that manual adjustment typically applies to all paper subsequently printed by the MFP.